Pipette assembly



Dec. 20, 1960 H. w. GERARDE PIPETTE ASSEMBLY 2 SheetsSheet 1 Filed Oct.9, 1958 INVENTOR.

HORACE w. age/mos Mme Mc/ Q a mmmy Dec. 20, 1960 H. w. GERARDE PIPETTEASSEMBLY 2 Sheets-Sheet 2 Filed Oct. 9, 1958 FIG. 7

FIG. 6

INVENTOR.

HORACE W GERARDE BY m, WMWMW 4/ MM ATTORNEYS United States PatentPIPETTE ASSEMBLY Horace William Gerarde, 508 Dorian Court, Westfield,NJ.

Filed Oct. 9, 1958, Ser. No. 766,215

Claims. (Cl. 2156) This invention relates to a structurally andfunctionally improved pipette assembly especially intended for use inconnection with blood counts.

It is an object of the invention to furnish a structure which will notrequire the services of a skilled operator, although the resultsobtained by the use of the improved apparatus will be entirely reliableand the accuracy may be depended upon.

Another object is that of providing a structure which will includerelatively few components each individually simple and rugged inconstruction and capable of ready assemblage to furnish an economicaland unitary apparatus. Accordingly, the assembly will have a one-timeuse, after which it is discarded. Therefore, the complicationsheretofore existing in connection with cleaning, sterilization, anddangers of inaccurate results obtained are completely avoided.

With these and other objects in mind, reference is had to the attachedsheets of drawings illustrating practical embodiments, and in which:

Fig. 1 is a sectional side view of a complete assembly prior to use;

Fig. 2 is a perspective view illustrating an initial step in thetechnique;

Fig. 3 is a sectional side view of the receptacle and shield of theassembly in separated condition;

Fig. 4 is a view similar to Fig. l, but showing an operational stepsubsequent to that illustrated in Fig. 3;

Fig. 5 is a similar view showing a still further operational step;

Fig. 6 illustrates the technique of expelling solution onto ahemocytometer;

Fig. 7 is a side elevation of the capillary and shield units inassociation with each other;

Fig. 8 is a view similar to Fig. 2, but showing a capillary unit ofslightly different construction; and

Fig. 9 is a sectional side View of a receptacle for use with the unit asillustrated in Fig. 8.

Referring primarily to Fig. 1, there has been illustrated a completeassembly in the form in which it will be initially presented to thetechnician. In that view, the capillary unit includes a tube 10preferably of glass and having a bore of accurate dimension. The upperend of this tube is secured to a bulb 11 having a vent opening 12. Thissecuring is conveniently effected by extending a portion of the bulb toprovide a plug or stoppering part 13. Bulb 11 is formed of rubber orplastic material having the characteristic of automatically restoring toits initial shape. Tube 10 having a uniform bore of small diameter, itfollows that for a given length of tube, a liquid column accuratelyconforming to a predetermined volume may be achieved by filling thatbore with liquid. In view of its small diameter, it will function as atrue capillary and cause liquid to automatically rise within it to apoint where it fills the complete tube.

A receptacle has been illustrated which conveniently takes form of abottle 14 of glass. Within this receptacle a volume of liquid diluent 15is disposed. The quantity of such liquid is accurately related to thecapacity of bore 10 so that the desired solution consistent with thetest being performed will be accurately achieved. The receptacle 14conveniently terminates in a neck portion 16. Disposed within thereceptacle is a mixing bead 17 formed of any suitable material andpreferably having a specific gravity such that it will sink through thebody of liquid 15 to the base of the receptacle.

As will be observed in Fig. 1, the diameter of the plug or stopperingportion 13 is less than the internal diameter of the neck 16. Also, ashield in the form of a tubular member 18 is provided, having its lowerend closed and its upper end open. This member is formed of any desiredmaterial such as a suitable plastic. It is preferably made with anoutstanding flange 19 adjacent its open end. This flange throughout onezone is continued as a tab 20.

The internal diameter of member 18 is such that it will accommodate theplug portion 13 snugly within its bore. The external diameter of thismember corresponds to the internal diameter of neck portion 16. Themajor portion of flange 19 may have a diameter equal to the externaldiameter of the neck, with tab 20 extending materially beyond thesurface of the latter. As shown, the length of tubular member 18 isadequate to accommodate the body of tube 10. The parts are proportionedso that ample space is provided for the pellet or mixing bead 17 to bepositioned within the receptacle without interference.

Substantially the same structures insofar as the capillary unit andreceptacle are concerned is shown in Figs. 3 and 9. In the first ofthese views, a tube 21 corresponding to ube 10 is provided. This tubehas attached to it a bulb 22 provided with a vent opening 23. In commonwith the structure shown in the earlier figures, this vent opening isdisposed in a surface of the bulb such that the finger of an operatormay engage that surface for the purpose of sealing the vent. Astoppering or plug portion 24 preferably forms a part of the bulb andgenerally corresponds to portion 13.

Insofar as the receptacle of Fig. 9 is concerned, it in volves asuitably shaped body 25 including a neck portion 26 normally closed by astopper 27. This stopper is formed of a material such as Teflon, andpreferably has a reduced outer end portion 28. Within the receptacle 25,a body of liquid diluent 29 is provided. The volume of that body isprecisely related to the volume of the liquid column defined by the boreof tube 21. It is preferred that the stopper 27 have such a specificgravity that it will sink through the body of liquid 29 and come to reston the base of the receptacle to thus function as a mixing bead.

Considering now the technique of using the device as shown in Fig. l,the operator will lance the finger of a patient, to produce on the skinsurface a drop of blood as shown in Fig. 2. At that time or priorthereto, the bulb 11 will have been grasped to withdraw the capillaryunit from receptacle 14. At the same time the shield 18 may be removed.This is effected by simply grasping tab 20 and exerting a pull to effectits withdrawal from the receptacle.

The outer end of tube 10 is immersed in the drop of blood. With the vent12 being unobstructed, blood will be automatically drawn upwardly withinthe bore of tube 10 under capillary action. The inflow into the borewill cease when the latter has been filled with blood.

The tube 10 is now introduced into the receptacle body and the vent 12is sealed by the finger, as shown in Fig. 4. Now, by compressing bulb11, the column of blood is forced from within tube 10 into the body ofdiluent 15. If thereupon, tube 10 has its lower end projected to a pointwhere it is immersed in the solution, a column of liquid will again bereestablished within the bore under capillary action.

masses Following this, the procedure illustrated in Fig. 4 may be againresorted to. With the repetition of these steps, it is apparent that thebore of the tube will be cleaned so that any blood which would tend toadhere to that bore will pass into the solution. Of course, a definitescavenging action may be resorted to bymaintaining the finger over thevent and releasing and compressing the bulb several times. .This,however, is liable to result in a condition such as has been shown inFig. 5, in which the bulb has been partially filled with the solution.Obviously, under those circumstances the capillary unit should bemanipulated to assure a substantially complete expulsion of any solutionwithin the bulb or the bore of tube 10. a I

Now, by agitating the assembly, the mixing bead or pellet 'will assistin the creation of a uniform solution. Thereafter, by aspirating thebulb a certain amount of solution may be drawn up into tube andsubsequently expelled out the surface of a hemacytometer 30, asillustrated in Fig. 6. Obviously, if instead of a' count beingimmediately resorted to, a physician desires to forward the solution toa laboratory, then the parts may be properly stoppered. This isachieved, for example, as in Fig. 3, after the establishment of thesolution by inserting shield 18 into the receptacle and thereuponinsertirig the tube and stoppering portion of the capillary unit intothe shield. Under these circumstances, the condition of the parts shownin Fig. 1 is reestablished. The solution will be amply protected and maybe used without difficulty by the laboratory technician.

Precisely the same general technique is followed in the use of theapparatus as shown in Figs. 8 and 9. In other words, under capillaryaction blood fills the bore of tube 21. However, an operator will pushinwardly on stopper 27 to cause the tapered Zone of the latter to lieadjacent the bore of neck 26. Under these circumstances, the stopperwill be freed from frictional retention by the receptacle wall and willdrop into the solution body 29 to function as a mixing pellet or bead.It will be observed that the plug or stoppcring portion 24 of bulb 22has a diameter corresponding to the bore face of neck 26. Therefore,with this stoppering portion disposed within the neck 26, it will ineifect seal the receptacle (except for the passage provided by vent 23)and will serve to retain the capillary unit in position.

Thus, among others, the several objects of the invention as specificallyaforenoted are achieved. Obviously, numerous changes in construction maybe resorted to and the steps of the method may be varied withoutdeparting from the spirit of the invention as defined by the claims.

Iclaim:

1. A pipette assembly including in combination a capillary tube having abore of constant cross-sectional area and of a reduced diameter suchthat liquid will rise throughout its length solely as a result ofsurface tension to furnish a liquid column of predetermined volume, acompressible bulb mounted by the upper tube end and formed with aventing opening such that the afore'stated rise of liquid may occur, areceptacle having an open end and to contain a diluent in a quantityprecisely related to the liquid volume of said capillary tube, and meansfor supporting such tube within said receptacle and with the bulbextending exteriorly thereof.

2. In an assembly as defined in claim 1, said bulb including a surfacecontactable with an operators finger to seal said opening, under whichconditions, pressing of said bulb will create air pressure interiorly ofsaid bulb.

3. In an assembly as defined in claim 2, said opening and surfaces beingincluded in an end of said bulb opposite such tube.

4. In an assembly as defined in claim 1, a tubular member having aclosed "and an open end, an outwardly extending fiange forming a part ofsaid member, said capillary tube extending into said member with saidbulb seating against its flange and said member projecting into saidreceptacle with its flange overlying and in engagement with the surfacesadjacent the open end of the latter.

5. In an assembly as defined in claim 4, the diameter of said flangebeing substantially equal to the diameter of the surfaces defining thereceptacle opening, and a tab portion projecting from said flangeradially of and beyond the receptacle surfaces.

References Cited in the file of this patent UNITED STATES PATENTS2,520,852 Myers Aug. 29, 1950 2,845,963 Zackheim Aug. 5, 1958 FQREIGNPATENTS 635,691 Germany Sept. 3, 1936 war rve

